SWR Static

My SM 400 has a static problem when I tweak almost every knob and even my slide EQ's. I've been working out of town for the last year, and haven't used that rig for that long. I was thinking maybe the pots needed cleaning, but surely they wouldn't all need it at the same time. I replaced the pre amp tube in my Redhead, and have never heard this sound in it. Is this the problem?